The invention pertains to control units for audible output devices in alarm systems. More particularly, the invention pertains to software driven control units which can provide a plurality of different audible outputs.
Known fire alarm systems usually indicate alarm conditions to building occupants via two methods: audible and visual. In many known systems, audible output is typically provided by sounder modules connected to fire alarm outputs.
The sounder modules provide fixed tone sequences selected by hardware methods. The sounder modules can only produce the preselected tone sequence when the fire alarm output turns it on.
Often two distinct tone sequences are required. For example, a slow tone for alert signaling and a fast tone for evacuation signaling. A common audible output signal for fire alarm systems is the temporal code. This code consists of a sound pattern of one second on followed by one second off, repeated continuously. Temporal audible coding is commonly used as an evacuation signal.
Hardware based sounders can be configured to produce the noted temporal code but they can not be reconfigured dynamically based on system conditions. A traditional fire alarm control module provides a simple on-off control to a sounder that produces the audible output for which it was configured.
FIG. 1 illustrates a prior art, hardware based sounder control configuration. In a system 10, as illustrated in FIG. 1, first and second control modules 12a, 12b are coupled to a common system, communication bus or link 14. Bus 14 could be dedicated to audible and/or visible output devices. Alternately, it could be the same bus to which system ambient condition detectors are coupled.
Each of modules 12a, 12b is hardware configured to respond to a different condition such as a fire alert or an evacuation. An output from each module 12a, b is coupled to a different input port of a multiple input sounder module 16. The sounder module 16 will be activated to produce the pre-selected audible output in response to a signal at a selected input from respective module 12a, b. In this implementation, the sounder module 16 includes multi-port input circuitry which responds to a common form of control signals, coupled to different ports, to drive the sounder in different ways to produce different audible outputs. The sounder 16 thus produces different drive signals, analog waveforms or digital pulses which in turn drive the output transducer.
In other known systems, the alarm system control unit, or, panel can provide a broader range of audible outputs by transmitting, on a loop basis, control pulses to the audible output devices. Such systems directly control the audible output devices, via local control circuitry by modulated pulse sequences transmitted on loops that are dedicated to those output devices.
There continues to be a need for more flexible control circuits for driving audible output devices. It would be desirable to be able to mix sensor modules, or detectors, with such control circuits on a common communications link. Preferably, the control circuits would be transparent to the common communications link.
In accordance with the invention, traditional audible output control in an alarm system is improved upon by placing the output sequencing under software control. This allows the respective alarm system to dynamically select the type of audible output as required. The system could be configured to produce an alert tone or an evacuation tone depending on conditions. Other output tones or visual outputs could also be produced.
In one aspect, an alarm system includes software driven, flexible audible signaling. An output module is coupled to a sound generating device such as a mechanical or electronic horn or a visual output device. The output module can be programmed to turn the drive to the output device with selected signals on and off in a particular sequence. This sequence produces a distinct audible pattern from the horn or a distinct visual sequence.
An advantage of a system in accordance with the invention is that the output generating signals can be coupled to relatively inexpensive output devices which do not have complex input circuits for providing various outputs. The software driven output modules can directly produce a plurality of different signals which can be coupled to the respective output devices, such as mechanical or electronic horns, to produce a plurality of different audible outputs. The output devices are thus simpler and less expensive.
A software driven output control module provides a programmable output signal. This output module is configured by downloading one or more control parameters from an alarm control unit or panel. Sets of parameters can include multiple audible or visible output signal sequences and the event controls to activate the sequences.
The audible or visual output sequence appropriate for any given system event could then be produced as needed. The control program for the respective module would select the appropriate output signal from those available in the module. The downloadable control parameter(s) for one or more output signals can be defined in various ways.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.